(archaeology,US, usually capitalized) A general term for the prehistoric period intermediate between the earliest period (‘Paleo-Indian’, ‘Paleo-American’, ‘American‐paleolithic’, &c.) of human presence in the Western Hemisphere, and the most recent prehistoric period (‘Woodland’, etc.).

1958, Wiley, Gordon R., and Philip Phillips, Method and Theory in American Archaeology, University of Chicago Press, Chicago, page #107:

[...] Archaic Stage [...] the stage of migratory hunting and gathering cultures continuing into environmental conditions approximately those of the present.

(paleoanthropology) (A member of) an archaic variety of Homo sapiens.

2009, The Human Lineage, page 432:

[...] prefer the third explanation for the advanced-looking features of Neandertals (Chapter 7) and the Ngandong hominins (Chapter 6), but they have had little to say about the post-Erectine archaics from China.

A person familiar with the dialect of certain portions of Massachusetts will not fail to recognize, in ordinary discourse, many words now noted in English vocabularies as archaic, the greater part of which were in common use about the time of the King James translation of the Bible. Shakespeare stands less in need of a glossary to most New Englanders than to many a native of the Old Country.

Almost every writer of power will occasionally use with strong effect an archaic term that he has unearthed from the treasures of the older English vocabulary. This is especially true of poets, who recognize that the unusualness of the archaic word will sometimes heighten the poetic effect.

When generations pass and the object or institution referred to by the archaic word is no longer part of present, lived experience, though the word has been retained, its meaning is commonly altered or simply vanishes. African talking drums, as used for example among the Lokele in eastern Zaire, speak in elaborate formulas that preserve certain archaic words which the drummers can vocalize but whose meaning they no longer know.

his resistance to censorship blends nicely with his scorn for the common folk, so a limited edition, in beautiful archaic language incomprehensible to the masses, of rude or blasphemous material such as one can find in the Decameron, would simultaneously satisfy both impulses.

Cabell also uses a kind of stylistic dissonance to reinforce his novel's thematic ironies at the sentence level. An inflated speech in archaic language might end with a modern pinprick: "And so on, and so on!"